A bolt device, in which a noncircular hole is formed in a member to be bolted and a bolt is provided with an engaging portion for engagement with a corner portion, and the like, of such noncircular hole for presenting rotation, is known.
The method for forming the noncircular hole in the member to be bolted is difficult and punching by means of a press can not be adopted to such method, in many cases.
Generally, a hole, through which a bolt is to be inserted, is opened by means of a drill. However, the hole, which can be drilled, is circular, so that, even though the bolt is provided with an engaging portion formed on the bolt body, the engaging portion does not engage the circular hole and rotation of the bolt is not prevented. Therefore, a nut has had to be threaded to the bolt by rotating the nut while fixing head of bolt by means of a spanner or wrench. This operation has been remarkably dangerous and difficult in an unstable building field, where are one hand can be used, and the like.